Running Aero on Vista Ultimate under parallels on a Mac

Hello all,

I have a new MacBOok Pro, fully up to date, with Parallels Desktop, also fully up to date. With the recent upgrade to Parallels, the software now supports DirectX graphics, and the hardware is sufficient for Aero. However, the steps required in teh Vista help files don't work (the Aero option doesn't exist in the settings (I get "appearance settings" instead of "window colour and appearance settings" - according to Vista Help, that's a bad sign ). An online tutorial instructed me to change a specific registry key, however it was already activated.

How do I get Aero up and running when it wasn't originally?

Thanks,

Aaron